There generally are four types of automotive driveline systems. More specifically, there exists a full-time front wheel drive system, a full-time rear wheel drive system, a part-time four-wheel drive system and an all-wheel drive system. Most commonly, the systems are distinguished by the delivery of power to different combinations of drive wheels, i.e., front drive wheels, rear drive wheels or some combination thereof. In addition to delivering power to a particular combination of drive wheels, most drive systems permit the respective driven wheels to rotate at different speeds. For example, when turning, the outside wheels generally rotate faster than the inside wheels and the front wheels generally rotate faster than the rear wheels.
Driveline systems also include one or more constant velocity joints (CVJ). Such joints, which include by way of example and not limitation, the plunging tripod type, a high speed fixed type, along with any other known types are well known to those skilled in the art and are employed where transmission of a constant velocity rotary motion is desired. A typical driveline system for a rear wheel or all-wheel drive vehicle, for example, incorporates one or more constant velocity joints to connect a pair of front and rear propeller shafts (propshafts). The propshafts transfer torque from a power take-off unit generally located about a front axle of the vehicle to a rear driveline module generally located about a rear axle of the vehicle. Similarly, a driveline system for a front wheel drive vehicle incorporates one or more constant velocity joints to transfer torque from the power take-off unit to the propshaft(s).
At certain rotational speeds and resonant frequencies the above referenced propshafts typically exhibit unbalanced rotation and thus undesirable vibrations. These vibrations traditionally result in bending or torsional forces within and along the length of the respective propshaft. Such bending or torsional forces as a result of the unbalanced rotation are neither desirable nor suitable in the operation of the driveline systems of most vehicles.
Accordingly, various dynamic dampers or mass dampers are utilized to suppress the undesirable vibrations that are induced in the rotary propshaft due to the unbalanced rotation. These dampers are often installed or inserted directly onto or into the propshaft. The dampers are designed to generate a prescribed vibrational frequency adjusted to the dominant frequency of the undesired vibrations. The damper converts or transfers the vibrational energy of the propshaft to the damper by resonance, and eventually absorbs the vibrational energy of the propshaft. Therefore, the damper attempts to cancel or negate the vibrations that are induced onto or caused by the rotary propshaft in normal operation of the driveline system of the vehicle.
Many dampers generally include a mass member disposed between a pair of ring-shaped fixing members and a pair of connecting members. The connecting members connect the ends of the fixing members to the mass members. However, many of these traditional dampers are not easily tunable to specific frequencies and have difficulty controlling damping without extensive redesign of the damper and the propshaft for each automotive vehicle driveline system. Further, many traditional dampers are developed for installation directly into the rotary propshaft. However, these dampers are not capable of being properly centered or aligned within the propshaft to create the desired damping effect.
Therefore, there is a need in the art for an improved internal absorber. There also is a need in the art for an internal absorber that uses both cantilever masses and constrained layer damping to create a dampening effect. There also is a need in the art for an internal absorber that is simple to install and modify to match specific frequencies and dampening levels of various vehicle driveline systems.